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Sanchez SE, Chiarelli TJ, Park MA, Carlyon JA. Orientia tsutsugamushi infection reduces host gluconeogenic but not glycolytic substrates. Infect Immun 2024:e0028424. [PMID: 39324805 DOI: 10.1128/iai.00284-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Accepted: 08/20/2024] [Indexed: 09/27/2024] Open
Abstract
Orientia tsutsugamushi a causal agent of scrub typhus, is an obligate intracellular bacterium that, akin to other rickettsiae, is dependent on host cell-derived nutrients for survival and thus pathogenesis. Based on limited experimental evidence and genome-based in silico predictions, O. tsutsugamushi is hypothesized to parasitize host central carbon metabolism (CCM). Here, we (re-)evaluated O. tsutsugamushi dependency on host cell CCM as initiated by glucose and glutamine. Orientia infection had no effect on host glucose and glutamine consumption or lactate accumulation, indicating no change in overall flux through CCM. However, host cell mitochondrial activity and ATP levels were reduced during infection and correspond with lower intracellular glutamine and glutamate pools. To further probe the essentiality of host CCM in O. tsutsugamushi proliferation, we developed a minimal medium for host cell cultivation and paired it with chemical inhibitors to restrict the intermediates and processes related to glucose and glutamine metabolism. These conditions failed to negatively impact O. tsutsugamushi intracellular growth, suggesting the bacterium is adept at scavenging from host CCM. Accordingly, untargeted metabolomics was utilized to evaluate minor changes in host CCM metabolic intermediates across O. tsutsugamushi infection and revealed that pathogen proliferation corresponds with reductions in critical CCM building blocks, including amino acids and TCA cycle intermediates, as well as increases in lipid catabolism. This study directly correlates O. tsutsugamushi proliferation to alterations in host CCM and identifies metabolic intermediates that are likely critical for pathogen fitness.IMPORTANCEObligate intracellular bacterial pathogens have evolved strategies to reside and proliferate within the eukaryotic intracellular environment. At the crux of this parasitism is the balance between host and pathogen metabolic requirements. The physiological basis driving O. tsutsugamushi dependency on its mammalian host remains undefined. By evaluating alterations in host metabolism during O. tsutsugamushi proliferation, we discovered that bacterial growth is independent of the host's nutritional environment but appears dependent on host gluconeogenic substrates, including amino acids. Given that O. tsutsugamushi replication is essential for its virulence, this study provides experimental evidence for the first time in the post-genomic era of metabolic intermediates potentially parasitized by a scrub typhus agent.
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Affiliation(s)
- Savannah E Sanchez
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Travis J Chiarelli
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Margaret A Park
- Department of Gastrointestinal Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida, USA
- Department of Biostatistics and Bioinformatics, H. Lee Moffitt Cancer Center, Tampa, Florida, USA
| | - Jason A Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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2
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Adcox HE, Hunt JR, Allen PE, Siff TE, Rodino KG, Ottens AK, Carlyon JA. Orientia tsutsugamushi Ank5 promotes NLRC5 cytoplasmic retention and degradation to inhibit MHC class I expression. Nat Commun 2024; 15:8069. [PMID: 39277599 PMCID: PMC11401901 DOI: 10.1038/s41467-024-52119-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 08/27/2024] [Indexed: 09/17/2024] Open
Abstract
How intracellular bacteria subvert the major histocompatibility complex (MHC) class I pathway is poorly understood. Here, we show that the obligate intracellular bacterium Orientia tsutsugamushi uses its effector protein, Ank5, to inhibit nuclear translocation of the MHC class I gene transactivator, NLRC5, and orchestrate its proteasomal degradation. Ank5 uses a tyrosine in its fourth ankyrin repeat to bind the NLRC5 N-terminus while its F-box directs host SCF complex ubiquitination of NLRC5 in the leucine-rich repeat region that dictates susceptibility to Orientia- and Ank5-mediated degradation. The ability of O. tsutsugamushi strains to degrade NLRC5 correlates with ank5 genomic carriage. Ectopically expressed Ank5 that can bind but not degrade NLRC5 protects the transactivator during Orientia infection. Thus, Ank5 is an immunoevasin that uses its bipartite architecture to rid host cells of NLRC5 and reduce surface MHC class I molecules. This study offers insight into how intracellular pathogens can impair MHC class I expression.
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Affiliation(s)
- Haley E Adcox
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, School of Medicine, Charlottesville, VA, USA
| | - Jason R Hunt
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA
| | - Paige E Allen
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA
| | - Thomas E Siff
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA
| | - Kyle G Rodino
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew K Ottens
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA
| | - Jason A Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, USA.
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3
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Raheem A, Lu D, Khalid AK, Zhao G, Fu Y, Chen Y, Chen X, Hu C, Chen J, Chen H, Guo A. The Identification of a Novel Nucleomodulin MbovP467 of Mycoplasmopsis bovis and Its Potential Contribution in Pathogenesis. Cells 2024; 13:604. [PMID: 38607043 PMCID: PMC11011252 DOI: 10.3390/cells13070604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 03/23/2024] [Accepted: 03/26/2024] [Indexed: 04/13/2024] Open
Abstract
Mycoplasmopsis bovis is a causative agent of crucial diseases in both dairy and beef cattle leading to substantial economic losses. However, limited control measures for M. bovis-related diseases exist due to a lack of understanding about the virulence factors of this pathogen, a common challenge in mycoplasma research. Consequently, this study aimed to characterize a novel nucleomodulin as a virulence-related factor of M. bovis. Employing bioinformatic tools, we initially predicted MbovP467 to be a secreted protein with a nuclear localization signal based on SignalP scores and the cNLS (Nuclear Localization Signal) Mapper, respectively. Subsequently, the MbovP467 gene was synthesized and cloned into a pEGFP plasmid with EGFP labeling to obtain a recombinant plasmid (rpEGFP-MbovP467) and then was also cloned in pET-30a with a consideration for an Escherichia coli codon bias and expressed and purified for the production of polyclonal antibodies against the recombinant MbovP467 protein. Confocal microscopy and a Western blotting assay confirmed the nuclear location of MbovP467 in bovine macrophages (BoMacs). RNA-seq data revealed 220 up-regulated and 20 down-regulated genes in the rpEGFP-MbovP467-treated BoMac group compared to the control group (pEGFP). A GO- and KEGG-enrichment analysis identified associations with inflammatory responses, G protein-coupled receptor signaling pathways, nuclear receptor activity, sequence-specific DNA binding, the regulation of cell proliferation, IL-8, apoptotic processes, cell growth and death, the TNF signaling pathway, the NF-κB signaling pathway, pathways in cancer, and protein families of signaling and cellular processes among the differentially expressed up-regulated mRNAs. Further experiments, investigating cell viability and the inflammatory response, demonstrated that MbovP467 reduces BoMac cell viability and induces the mRNA expression of IL-1β, IL-6, IL-8, TNF-α, and apoptosis in BoMac cells. Further, MbovP467 increased the promoter activity of TNF-α. In conclusion, this study identified a new nucleomodulin, MbovP467, for M. bovis, which might have an important role in M. bovis pathogenesis.
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Affiliation(s)
- Abdul Raheem
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Doukun Lu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Abdul Karim Khalid
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Gang Zhao
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, School of Life Sciences, Ningxia University, Yinchuan 750021, China;
| | - Yingjie Fu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yingyu Chen
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xi Chen
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Changmin Hu
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Jianguo Chen
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Huanchun Chen
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Aizhen Guo
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; (A.R.); (D.L.); (A.K.K.); (Y.F.); (Y.C.); (X.C.); (C.H.); (J.C.); (H.C.)
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
- Hubei International Scientific and Technological Cooperation Base of Veterinary Epidemiology, Huazhong Agricultural University, Wuhan 430070, China
- International Research Center for Animal Disease, Ministry of Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
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Giengkam S, Kullapanich C, Wongsantichon J, Adcox HE, Gillespie JJ, Salje J. Orientia tsutsugamushi: comprehensive analysis of the mobilome of a highly fragmented and repetitive genome reveals the capacity for ongoing lateral gene transfer in an obligate intracellular bacterium. mSphere 2023; 8:e0026823. [PMID: 37850800 PMCID: PMC10732058 DOI: 10.1128/msphere.00268-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/22/2023] [Indexed: 10/19/2023] Open
Abstract
IMPORTANCE Obligate intracellular bacteria, or those only capable of growth inside other living cells, have limited opportunities for horizontal gene transfer with other microbes due to their isolated replicative niche. The human pathogen Ot, an obligate intracellular bacterium causing scrub typhus, encodes an unusually high copy number of a ~40 gene mobile genetic element that typically facilitates genetic transfer across microbes. This proliferated element is heavily degraded in Ot and previously assumed to be inactive. Here, we conducted a detailed analysis of this element in eight Ot strains and discovered two strains with at least one intact copy. This implies that the element is still capable of moving across Ot populations and suggests that the genome of this bacterium may be even more dynamic than previously appreciated. Our work raises questions about intracellular microbial evolution and sounds an alarm for gene-based efforts focused on diagnosing and combatting scrub typhus.
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Affiliation(s)
- Suparat Giengkam
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Chitrasak Kullapanich
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Jantana Wongsantichon
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Haley E. Adcox
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Joseph J. Gillespie
- Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland, USA
| | - Jeanne Salje
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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Bui DC, Luo T, McBride JW. Type 1 secretion system and effectors in Rickettsiales. Front Cell Infect Microbiol 2023; 13:1175688. [PMID: 37256108 PMCID: PMC10225607 DOI: 10.3389/fcimb.2023.1175688] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/02/2023] [Indexed: 06/01/2023] Open
Abstract
Obligate intracellular bacteria in the order Rickettsiales are transmitted by arthropod vectors and cause life-threatening infections in humans and animals. While both type 1 and type 4 secretion systems (T1SS and T4SS) have been identified in this group, the most extensive studies of Rickettsiales T1SS and associated effectors have been performed in Ehrlichia. These studies have uncovered important roles for the T1SS effectors in pathobiology and immunity. To evade innate immune responses and promote intracellular survival, Ehrlichia and other related obligate pathogens secrete multiple T1SS effectors which interact with a diverse network of host targets associated with essential cellular processes. T1SS effectors have multiple functional activities during infection including acting as nucleomodulins and ligand mimetics that activate evolutionarily conserved cellular signaling pathways. In Ehrlichia, an array of newly defined major immunoreactive proteins have been identified that are predicted as T1SS substrates and have conformation-dependent antibody epitopes. These findings highlight the underappreciated and largely uncharacterized roles of T1SS effector proteins in pathobiology and immunity. This review summarizes current knowledge regarding roles of T1SS effectors in Rickettsiales members during infection and explores newly identified immunoreactive proteins as potential T1SS substrates and targets of a protective host immune response.
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Affiliation(s)
- Duc-Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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6
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Giengkam S, Kullapanich C, Wongsantichon J, Adcox HE, Gillespie JJ, Salje J. Orientia tsutsugamushi: analysis of the mobilome of a highly fragmented and repetitive genome reveals ongoing lateral gene transfer in an obligate intracellular bacterium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.11.540415. [PMID: 37215039 PMCID: PMC10197636 DOI: 10.1101/2023.05.11.540415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The rickettsial human pathogen Orientia tsutsugamushi (Ot) is an obligate intracellular Gram-negative bacterium with one of the most highly fragmented and repetitive genomes of any organism. Around 50% of its ~2.3 Mb genome is comprised of repetitive DNA that is derived from the highly proliferated Rickettsiales amplified genetic element (RAGE). RAGE is an integrative and conjugative element (ICE) that is present in a single Ot genome in up to 92 copies, most of which are partially or heavily degraded. In this report, we analysed RAGEs in eight fully sequenced Ot genomes and manually curated and reannotated all RAGE-associated genes, including those encoding DNA mobilisation proteins, P-type (vir) and F-type (tra) type IV secretion system (T4SS) components, Ankyrin repeat- and tetratricopeptide repeat-containing effectors, and other piggybacking cargo. Originally, the heavily degraded Ot RAGEs led to speculation that they are remnants of historical ICEs that are no longer active. Our analysis, however, identified two Ot genomes harbouring one or more intact RAGEs with complete F-T4SS genes essential for mediating ICE DNA transfer. As similar ICEs have been identified in unrelated rickettsial species, we assert that RAGEs play an ongoing role in lateral gene transfer within the Rickettsiales. Remarkably, we also identified in several Ot genomes remnants of prophages with no similarity to other rickettsial prophages. Together these findings indicate that, despite their obligate intracellular lifestyle and host range restricted to mites, rodents and humans, Ot genomes are highly dynamic and shaped through ongoing invasions by mobile genetic elements and viruses.
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Affiliation(s)
- Suparat Giengkam
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Chitrasak Kullapanich
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Jantana Wongsantichon
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Haley E. Adcox
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Joseph J. Gillespie
- Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, MD 21201
| | - Jeanne Salje
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Pathology, Department of Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, UK
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Gillespie JJ, Salje J. Orientia and Rickettsia: different flowers from the same garden. Curr Opin Microbiol 2023; 74:102318. [PMID: 37080115 DOI: 10.1016/j.mib.2023.102318] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/22/2023]
Abstract
Recent discoveries of basal extracellular Rickettsiales have illuminated divergent evolutionary paths to host dependency in later-evolving lineages. Family Rickettsiaceae, primarily comprised of numerous protist- and invertebrate-associated species, also includes human pathogens from two genera, Orientia and Rickettsia. Once considered sister taxa, these bacteria form distinct lineages with newly appreciated lifestyles and morphological traits. Contrasting other rickettsial human pathogens in Family Anaplasmataceae, Orientia and Rickettsia species do not reside in host-derived vacuoles and lack glycolytic potential. With only a few described mechanisms, strategies for commandeering host glycolysis to support cytosolic growth remain to be discovered. While regulatory systems for this unique mode of intracellular parasitism are unclear, conjugative transposons unique to Orientia and Rickettsia species provide insights that are critical for determining how these obligate intracellular pathogens overtake eukaryotic cytosol.
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Affiliation(s)
- Joseph J Gillespie
- Department of Microbiology and Immunology, School of Medicine, University of Maryland Baltimore, USA.
| | - Jeanne Salje
- Department of Biochemistry, Department of Pathology, and Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK.
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Read CB, Lind MCH, Chiarelli TJ, Izac JR, Adcox HE, Marconi RT, Carlyon JA. The Obligate Intracellular Bacterial Pathogen Anaplasma phagocytophilum Exploits Host Cell Multivesicular Body Biogenesis for Proliferation and Dissemination. mBio 2022; 13:e0296122. [PMID: 36409075 PMCID: PMC9765717 DOI: 10.1128/mbio.02961-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 10/26/2022] [Indexed: 11/23/2022] Open
Abstract
Anaplasma phagocytophilum is the etiologic agent of the emerging infection, granulocytic anaplasmosis. This obligate intracellular bacterium lives in a host cell-derived vacuole that receives membrane traffic from multiple organelles to fuel its proliferation and from which it must ultimately exit to disseminate infection. Understanding of these essential pathogenic mechanisms has remained poor. Multivesicular bodies (MVBs) are late endosomal compartments that receive biomolecules from other organelles and encapsulate them into intralumenal vesicles (ILVs) using endosomal sorting complexes required for transport (ESCRT) machinery and ESCRT-independent machinery. Association of the ESCRT-independent protein, ALIX, directs MVBs to the plasma membrane where they release ILVs as exosomes. We report that the A. phagocytophilum vacuole (ApV) is acidified and enriched in lysobisphosphatidic acid, a lipid that is abundant in MVBs. ESCRT-0 and ESCRT-III components along with ALIX localize to the ApV membrane. siRNA-mediated inactivation of ESCRT-0 and ALIX together impairs A. phagocytophilum proliferation and infectious progeny production. RNA silencing of ESCRT-III, which regulates ILV scission, pronouncedly reduces ILV formation in ApVs and halts infection by arresting bacterial growth. Rab27a and its effector Munc13-4, which drive MVB trafficking to the plasma membrane and subsequent exosome release, localize to the ApV. Treatment with Nexinhib20, a small molecule inhibitor that specifically targets Rab27a to block MVB exocytosis, abrogates A. phagocytophilum infectious progeny release. Thus, A. phagocytophilum exploits MVB biogenesis and exosome release to benefit each major stage of its intracellular infection cycle: intravacuolar growth, conversion to the infectious form, and exit from the host cell. IMPORTANCE Anaplasma phagocytophilum causes granulocytic anaplasmosis, a globally emerging zoonosis that can be severe, even fatal, and for which antibiotic treatment options are limited. A. phagocytophilum lives in an endosomal-like compartment that interfaces with multiple organelles and from which it must ultimately exit to spread within the host. How the bacterium accomplishes these tasks is poorly understood. Multivesicular bodies (MVBs) are intermediates in the endolysosomal pathway that package biomolecular cargo from other organelles as intralumenal vesicles for release at the plasma membrane as exosomes. We discovered that A. phagocytophilum exploits MVB biogenesis and trafficking to benefit all aspects of its intracellular infection cycle: proliferation, conversion to its infectious form, and release of infectious progeny. The ability of a small molecule inhibitor of MVB exocytosis to impede A. phagocytophilum dissemination indicates the potential of this pathway as a novel host-directed therapeutic target for granulocytic anaplasmosis.
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Affiliation(s)
- Curtis B. Read
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Mary Clark H. Lind
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Travis J. Chiarelli
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Jerilyn R. Izac
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Haley E. Adcox
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Richard T. Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
| | - Jason A. Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, Virginia, USA
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9
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Orientia tsutsugamushi OtDUB Is Expressed and Interacts with Adaptor Protein Complexes during Infection. Infect Immun 2022; 90:e0046922. [PMID: 36374099 PMCID: PMC9753657 DOI: 10.1128/iai.00469-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Orientia tsutsugamushi is an etiologic agent of scrub typhus, a globally emerging rickettsiosis that can be fatal. The bacterium's obligate intracellular lifestyle requires its interaction with host eukaryotic cellular pathways. The proteins it employs to do so and their functions during infection are understudied. Recombinant versions of the recently characterized O. tsutsugamushi deubiquitylase (OtDUB) exhibit high-affinity ubiquitin binding, mediate guanine nucleotide exchange to activate Rho GTPases, bind clathrin adaptor protein complexes 1 and 2, and bind the phospholipid phosphatidylserine. Whether OtDUB is expressed and its function during O. tsutsugamushi infection have yet to be explored. Here, OtDUB expression, location, and interactome during infection were examined. O. tsutsugamushi transcriptionally and translationally expresses OtDUB throughout infection of epithelial, monocytic, and endothelial cells. Results from structured illumination microscopy, surface trypsinization of intact bacteria, and acetic acid extraction of non-integral membrane proteins indicate that OtDUB peripherally associates with the O. tsutsugamushi cell wall and is at least partially present on the bacterial surface. Analyses of the proteins with which OtDUB associates during infection revealed several known O. tsutsugamushi cell wall proteins and others. It also forms an interactome with adapter protein complex 2 and other endosomal membrane traffic regulators. This study documents the first interactors of OtDUB during O. tsutsugamushi infection and establishes a strong link between OtDUB and the host endocytic pathway.
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OtDUB from the Human Pathogen Orientia tsutsugamushi Modulates Host Membrane Trafficking by Multiple Mechanisms. Mol Cell Biol 2022; 42:e0007122. [PMID: 35727026 PMCID: PMC9302166 DOI: 10.1128/mcb.00071-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Host cell membrane-trafficking pathways are often manipulated by bacterial pathogens to gain cell entry, avoid immune responses, or to obtain nutrients. The 1,369-residue OtDUB protein from the obligate intracellular human pathogen Orientia tsutsugamushi bears a deubiquitylase (DUB) and additional domains. Here we show that OtDUB ectopic expression disrupts membrane trafficking through multiple mechanisms. OtDUB binds directly to the clathrin adaptor-protein (AP) complexes AP-1 and AP-2, and the OtDUB275-675 fragment is sufficient for binding to either complex. To assess the impact of OtDUB interactions with AP-1 and AP-2, we examined trans-Golgi trafficking and endocytosis, respectively. Endocytosis is reduced by two separate OtDUB fragments: one contains the AP-binding domain (OtDUB1-675), and the other does not (OtDUB675-1369). OtDUB1-675 disruption of endocytosis requires its ubiquitin-binding capabilities. OtDUB675-1369 also fragments trans- and cis-Golgi structures. Using a growth-based selection in yeast, we identified viable OtDUB675-1369 point mutants that also no longer caused Golgi defects in human cells. In parallel, we found OtDUB675-1369 binds directly to phosphatidylserine, and this lipid binding is lost in the same mutants. Together these results show that OtDUB contains multiple activities capable of modulating membrane trafficking. We discuss how these activities may contribute to Orientia infections.
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Kim Y, Wang J, Clemens EG, Grab DJ, Dumler JS. Anaplasma phagocytophilum Ankyrin A Protein (AnkA) Enters the Nucleus Using an Importin-β-, RanGTP-Dependent Mechanism. Front Cell Infect Microbiol 2022; 12:828605. [PMID: 35719343 PMCID: PMC9204287 DOI: 10.3389/fcimb.2022.828605] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 04/20/2022] [Indexed: 12/30/2022] Open
Abstract
Anaplasma phagocytophilum, a tick-borne obligately intracellular bacterium of neutrophils, causes human granulocytic anaplasmosis. Ankyrin A (AnkA), an effector protein with multiple ankyrin repeats (AR) is injected via type IV-secretion into the host neutrophil to gain access to the nucleus where it modifies the epigenome to promote microbial fitness and propagation. AR proteins transported into the host cell nucleus must use at least one of two known eukaryotic pathways, the classical importin β-dependent pathway, and/or the RanGDP- and AR (ankyrin-repeat)-dependent importin β-independent (RaDAR) pathway. Truncation of the first four AnkA N-terminal ARs (AR1-4), but not other regions, prevents AnkA nuclear accumulation. To investigate the mechanism of nuclear import, we created point mutations of AnkA N-terminal ARs, predicted to interfere with RaDAR protein import, and used importazole, a specific inhibitor of the importin α/β, RanGTP-dependent pathway. Nuclear colocalization analysis shows that nuclear localization of AnkA is unaffected by single AR1-4 mutations but is significantly reduced by single mutations in consecutive ARs suggesting RaDAR protein nuclear import. However, AnkA nuclear localization was also decreased with importazole, and with GTPγS. Furthermore, A. phagocytophilum growth in HL-60 cells was completely suppressed with importazole, indicating that A. phagocytophilum propagation requires a β-importin-dependent pathway. A typical classical NLS overlapping AR4 was subsequently identified suggesting the primacy of the importin-α/β system in AnkA nuclear localization. Whether the mutational studies of putative key residues support RaDAR NLS function or simply reflect structural changes that diminish engagement of an AR-NLS-importin pathway needs to be resolved through careful structure-function studies.
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Affiliation(s)
- Yuri Kim
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Jianyang Wang
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Emily G. Clemens
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Dennis J. Grab
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - J. Stephen Dumler
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States,*Correspondence: J. Stephen Dumler,
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Functional Characterization of Non-Ankyrin Repeat Domains of Orientia tsutsugamushi Ank Effectors Reveals Their Importance for Molecular Pathogenesis. Infect Immun 2022; 90:e0062821. [PMID: 35435726 DOI: 10.1128/iai.00628-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Orientia tsutsugamushi is a genetically intractable obligate intracellular bacterium, causes scrub typhus, and has one of the largest known armamentariums of ankyrin repeat-containing effectors (Anks). Most have a C-terminal F-box presumed to interact with the SCF ubiquitin ligase complex primarily based on their ability to bind overexpressed Skp1. Whether all F-box-containing Anks bind endogenous SCF components and the F-box residues essential for such interactions has gone unexplored. Many O. tsutsugamushi Ank F-boxes occur as part of a PRANC (pox protein repeats of ankyrin-C-terminal) domain. Roles of the non-F-box portion of the PRANC and intervening sequence region (ISR) that links the ankyrin repeat and F-box/PRANC domains are unknown. The functional relevance of these effectors' non-ankyrin repeat domains was investigated. The F-box was necessary for Flag-tagged versions of most F-box-containing Anks to precipitate endogenous Skp1, Cul1, and/or Rbx1, while the ISR and PRANC were dispensable. Ank toxicity in yeast was predominantly F-box dependent. Interrogations of Ank1, Ank5, and Ank6 established that L1, P2, E4, I9, and D17 of the F-box consensus are key for binding native SCF components and for Ank1 and Ank6 to inhibit NF-κB. The ISR is also essential for Ank1 and Ank6 to impair NF-κB. Ectopically expressed Ank1 and Ank6 lacking the ISR or having a mutagenized F-box incapable of binding SCF components performed as dominant-negative inhibitors to block O. tsutsugamushi NF-κB modulation. This study advances knowledge of O. tsutsugamushi Ank functional domains and offers an approach for validating their roles in infection.
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Matos AL, Curto P, Simões I. Moonlighting in Rickettsiales: Expanding Virulence Landscape. Trop Med Infect Dis 2022; 7:32. [PMID: 35202227 PMCID: PMC8877226 DOI: 10.3390/tropicalmed7020032] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/05/2022] [Accepted: 02/17/2022] [Indexed: 12/22/2022] Open
Abstract
The order Rickettsiales includes species that cause a range of human diseases such as human granulocytic anaplasmosis (Anaplasma phagocytophilum), human monocytic ehrlichiosis (Ehrlichia chaffeensis), scrub typhus (Orientia tsutsugamushi), epidemic typhus (Rickettsia prowazekii), murine typhus (R. typhi), Mediterranean spotted fever (R. conorii), or Rocky Mountain spotted fever (R. rickettsii). These diseases are gaining a new momentum given their resurgence patterns and geographical expansion due to the overall rise in temperature and other human-induced pressure, thereby remaining a major public health concern. As obligate intracellular bacteria, Rickettsiales are characterized by their small genome sizes due to reductive evolution. Many pathogens employ moonlighting/multitasking proteins as virulence factors to interfere with multiple cellular processes, in different compartments, at different times during infection, augmenting their virulence. The utilization of this multitasking phenomenon by Rickettsiales as a strategy to maximize the use of their reduced protein repertoire is an emerging theme. Here, we provide an overview of the role of various moonlighting proteins in the pathogenicity of these species. Despite the challenges that lie ahead to determine the multiple potential faces of every single protein in Rickettsiales, the available examples anticipate this multifunctionality as an essential and intrinsic feature of these obligates and should be integrated into available moonlighting repositories.
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Affiliation(s)
- Ana Luísa Matos
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; (A.L.M.); (P.C.)
| | - Pedro Curto
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; (A.L.M.); (P.C.)
| | - Isaura Simões
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; (A.L.M.); (P.C.)
- IIIUC—Institute of Interdisciplinary Research, University of Coimbra, 3004-504 Coimbra, Portugal
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